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Dec. 20, 1927.

F. A. CANON ET AL PROCESS 6F CARRYING ON CATALYTIC REAGTIOIS Orizina; Filed June 20. 1922- mama, Dec. 20,

UNITED S ATES lam-24;

' rm]: A- GLITCH CHEBTEB E. ANDREWS, OI PITTSSU 'BGH; VLHIA, A8- BIGNOBB TO THE BELDEN COMPANY, 01 PITTSBUBGH, PENNSYLVANIA, I 00330- mrrox or nnnawm.

ra'ocass or omxme on caranx'rrc mac-axon ori ami Io, 1,014,105, aim Januar 11, 1927, semi sarcoma, filed June :0, 1m. Application .10!

' reissue fled April 38, 1927. Serial Io. 185,908.

In the art of exothermic chemical reactlons ver practical difijculties have been experlence 1n dissipating the excessive heat thereby generated.

The catalytic air oxidation of anthracene to anthratkuinone is an "example of such a reaction. 11 that process the optimum temperature is above 450 tween 450 C. and 550 0., 1 ing roughly be- I outexothermic chemical reactions. of 'this character. which will permit the zone of reaction to reach and maintain a desired op- 'erating temperature, but will preventits rise to an a normal degree thereabove, the

process being substantially automatic in operation.

In processes of the above character in which the lower operating temperatures ob tain. water has been emp oyed as a cooling 80 agent, and in some respects'has ideal char-' acteristics. It is easily obtained, has great thermal capacity and can be conveniently-directed and controlled. If properly brought into heat transferring relationship to the catalyst and the reaction vapors, itwill be caused to boil.

sorption of great quantities of heat from the catalyst and the "reactin gases because of the large amount ofheat ,(latent heat of vaporization) required to effect its boiling operation.

The use of mercury hfifibeen ropose'd but this material presents serious di culties. In

.the first place its boiling oint is too low .for. 4 successful application wit out special though well-known methods of treatment which add ration. Its highmaterially to the cost of o cost makes unlimited use, ike that of water,

rohibitive. In'addition it has a relatively 50 ow degree of heat absorption and a relatively lowrate of heat conductivity. It is also subject to oxidation andits high spe- I ut much higher 10 temperatures will automatically build up This will result in the abcific gravity necessitates special and costly means for supporting and containing it.

In carrying out the resent invention we have discovered thati a composite metal consisting of one or more metals thatwill boil below the desired temperture of. the reaction and one or more metals that will boil above the said desired temperature of the reaction, is formed in roper proportions, "and this composite metal isplaced in heattransferring relation to the catalyst and the reacting gases. it will be caused 'to boil at a temperature close to but slightl' below 'the desired temperature of the reaction and may be thus made to control the temperature of the reaction and keep the same well within maximum limits while permitting it to reach and'maintain. an efiicient minimum. It will be apparent that themethod of the present metal alloys. metal will have a low melting point, great themalcapacity and conductivity and relatively light specific gravity.

Taking'the air oxidation process of conyerting naphthalene to phthalic anhydride as an example of the practical application of the invention. a heated mixture of air or other oxygen containing gas and naphthalene in'the-vapor phase and .at a suitable temperature is brought into the presence of a-suitable catalyst-for instance, vanadium oxide. The nahpthalene is thereby con- .verted into hthalic anhydride and a large amount "of eat is thereby generated, re-- sulting in high temperatures. unless Controlled. The reaction temperature as above stated should run between 400 and 450 C. and the desired temperature for-the'most efi'ec'tive working of this conversion is ordinarily at approximately 425 in the boiling point range of the composite In addition this composite PATENT OEFICE.;I

v-iously temperatures materially above the same arenot only undesirable but experience has demonstrated that very high tempera 'ture is detrimental to the-product and apt to.

disastrous to the reaction at! aratus.

If cadmium"'whi'ch boils at 8 0., and mercurywhich has a boilingpoint at 857 "C. be mixed in propcrtionsacomf and by weight of mercu position can be obtained having a boilin pointwhich is close to that of the, desir reaction temperature. made up of 12%, by weight, of cadmium and 88% by weight of mercury, is semili'quid at 20Cvand has a boiling point of approximately 370? I 0., whereas 40% by weight, of cadmium combined with 60% by weight, of mercury is liquid at about 151 1 .C. and boils at approximately 430 C. If

a working reaction temperature of approximately 425 C. is taken as satisfactory, a boiling temperature of about 400 C. for the-controll ng composition is substantially satisfactory, and this can be obtained by a mixture of 25%, by weight of cadmium This particular mixture is liquid at a out C. The composition has other valuable features besides that of itsboiling point. While the thermal conductivity of mercury is relatively low (.0189) that of cadmium is .215, so that the thermal conductivity of the comosition. is high, which is an important actor that assists it in its heat-dissipatin ualities. Moreover the specificv avlty o t e composition is less than that o mercury, the latter being 13.5 while cadmium is 8.6. In practicin the process the composite metal .is broug tinto heat transferring relation to the zone of reaction by any suitable or obvious means being held in a suitable container through the walls of which the heat ofreaction will pass to the metal, causing the latter to boil and thereby absorb such heat. The vapors thus generated ma be collected, condensed and returned to lieat transferring relationship to the zone of reaction for reuse, the low melting point of the metal making this easy of accomplishment.

Thus in the accompanying drawings: Figure 1 is a vertical sectional view diagrammatic in character of a type of apparatus-for carrying out the process,

Figure 2 is a cross sectional view of the same.

.A chamber 3 containin provided with an inlet 5,

acatal 4is ugh w 'ch the preheated gases as above'descnbed are in-v troduced, and an outlet 5 from which the treated ases pass for further treatment. Inside t is chamber is a container 6 in which the composite metal 7 is placed; The vapors from the boiling metal 7 rise to a condenser 8 which may be jacketed as shown at i 9 to hold a cooling medium of lower boiling point, as forexaniple, water. 'The .water may be made to boil in performing its condensing operation andthesteam thus generated or the heat-absorbed employed in turn for any useful'purposes desired. The com-.

position,' howe ver, having a low meltin' point, will mamtam. a fluid candition an consequently gravitate back toheat trans- The same. Thus a composltlon mesa ferring relationship to the zone of reaction.

process may be successfully carried out in the catalytic oxidation of anthracene to anthraquinone. In that process anthracene in the vapor phase and mixed with air or other oxygen containing as in pro erly heated condition is' broug t into tie pressure of a catalyst, for nstance'molyb- Y enum oxide. lies between 450 C. and 550 C. therefore, approximately 515 C. is taken as a. desired working-tem rature, a composition of 60% b weight 0 cadmium and 40% by wei ht o mercury will give a boilingpoint of a ut 492 C. I This process canthus be successfully car-' ried out with the a paratus of the as that above sug esteg for the phthalic anhy ide and is o portance for the purpose of producing anthraquinone, since so far as we areaware no satisfactory catalytic oxidation process of this character has been commercially practicable because of. the difliculties of controllin the high temperatures necessary to the satisfactory working of theprocess with the materials used as controlling substances up to this time. 7

What we claim, is: i

1. The process of carrying on exothermic chemical reactions at temperatures within The optimum tem erature' reduction of decided imthe range of boiling points of alloys containing cadmium and mercury, which comprises transmitting excess heat exothermically generated to an alloy consisting substantial] entirely of cadmium and mercury which boil at the temperature desired, and boiling said alloy by means of said excess heat.

2. The process of ca g on catalytic reactions, which consists in carrying on an exothermic vapor hase catalytic reaction at a temperature fal '%within the range of boiling oints of ca ium and mercury alloys, an maintaining such temperature by transmitting the excess heat exothermically generated to a com osition consisting substantially entirely o cadmium and mere which will boil when said temperature is reached and boiling said composition by said excess heat.

3. The rocess of carrying on catalytic reactio othermic vapor phase catalytic reaction at a temperature between 870 C. and 450 9., and maintaining such temperature b transmitting the excess heat'exothermical l generated to a composition cons'ist' su antially entirely of um an mercury that will boil when said temperature is ence of a heated catalyst at a w ich consists in carrying on an ex-- r 7 ap roximately between-400C; and oxygen containing gas to a catalyst at a 7 550 an maintaining such temperature wor ing temperature ran g ap runby transmitting the'excess-heat ex'othermis mately between 450 C. an 550 and cally generated to a com 'tion of cadmium maintaining said temperature by transmit- 5 and mercury that will il when said temting the excess heat erated to a compoei- 15 perature is reached, and boiling said comtion of cadmium an mercury that will boil position by said excess heat. at said temperature. a

5. The process of converting anthracene to anthraquinone which consists in subject- FBANK A. CANON. ing a mixture of anthracene vapor an an CHESTER E. ANDREWS. v 

